Ensure that the focus ring in the bookmarks bar does not paint outside the parent view

The proposed fix is to notify the parent views when a child enables layering. The parent in this case the ScrollView overrides the newly added notification OnChildLayerChanged() and enablesviewport layering. This ensures that the ring gets clipped.

Longer term it seems like the focus ring should really be a property of the view and should not be instantiated by different controls all over the place.